The powered surgical saw has evolved into an important surgical tool. A typical powered surgical saw includes a motor that, through a drive mechanism, causes a complementary blade to move in a repeating pattern. Powered surgical saws have become very efficient tools for cutting into both hard tissue, commonly referred to as bone, and soft tissue.
When a surgical saw is used, it should only cut the tissue it is intended to cut; the saw blade should not cut into the surrounding tissue. A class of saw accessories, referred to as blade guards, prevent a surgical saw blade from penetrating tissue other than that the blade is intended to cut. One particular blade guard has been developed for use with a sternum saw. The sternum is the bone that extends down the front of the chest of an individual. The sternum is the bone that covers organs such as the thorax and heart as well as parts of the lungs and liver. In order to gain access to these soft tissue organs, the sternum saw is employed to cut and separate the sternum. The complementary blade guard prevents the end of the blade from penetrating the underlying soft tissue organs. A typical sternum guard is a one-piece unit that has three separate components. The first of these components is the body. This is the component that connects the blade guard to the complementary saw with which it is used. The second component is an elongated leg. The leg extends outwardly from the body and is positioned behind the trailing edge of the associated saw blade. A foot is connected to the distal end of the leg. The foot extends forward from the leg and is formed with an opening in which the end of the blade is located. The leg and foot are dimensioned so that, during actuation of the blade, the blade does not extend out of either the distal or proximal ends of the foot. Since the end of the blade is encapsulated in the foot, the possibility that the blade will inadvertently cut any of the tissue underneath the sternum is essentially eliminated.
While current blade guards prevent the unintended cutting of tissue by the ends of the blades with which they are used, there are some disadvantages associated with their use. Some current blade guards are provided with legs that are formed out of thin, flat pieces of metal. This is because the space in which a blade guard travels, the kerf in the bone cut by the blade, is itself relatively narrow. For example, some sternum blade have thickness ranging between 36 to 44 mils (0.036 to 0.044 inches). The associated legs are often constructed to be approximately 25 mils thick. The reason the blade guard legs are even thinner than the blades themselves is that, during surgery, the surrounding tissue has a tendency to move the separated sections of the sternum back together. Moreover, sometimes a surgeon cuts the bone so that the kerf has a non-linear profile. Owing to the curved or angled profile of these kerfs, it can be difficult to maneuver a flat blade guard through them. Therefore, to ensure that the leg can freely travel in the kerf, the leg should be thinner than the saw blade that forms the kerf.
A problem with making a leg this thin is that it is structurally a weak component. Consequently, if a leg is subjected to significant lateral pressure, it is prone to bend. Such bending naturally causes the associated foot to move out of alignment with the blade with which the blade guard is intended for use. Also, once this misalignment occurs, the blade guard may strike the blade. Also as a result of misalignment, the blade guard may bear against the bone. Once either of these events occur, significant heat may be generated at the blade guard-blade or blade guard-bone interface. Should the blade guard abut the moving blade, a significant amount of noise may also be generated. Moreover, in some circumstances, the pressing of the blade guard against either the blade or the bone may inhibit the cutting action of the surgical tool. Thus, once a blade guard falls out of alignment with the associated blade, the blade guard may no longer be useful for its intended purpose.